


Better Living Through Chemistry

by verdant_fire



Category: Sherlock (TV)
Genre: Chemistry, Chemistry Kink, First Kiss, First Time, For Science!, Johnlock Roulette, London, Longing, M/M, POV Sherlock Holmes, Pining, Pining Sherlock, Romance, Science, Science Kink, Scientist Sherlock, Sherlock's Violin, or at least Sherlock's version of it
Language: English
Status: Completed
Published: 2015-01-02
Updated: 2015-01-02
Packaged: 2018-03-04 21:49:28
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,764
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3091730
Author URL: https://archiveofourown.org/users/verdant_fire/pseuds/verdant_fire
Summary: <blockquote class="userstuff">
              <p>When Sherlock cares about something, he analyses it, takes it apart piece by piece.  He dreams about doing the same to John.</p>
            </blockquote>





	Better Living Through Chemistry

**Author's Note:**

  * For [dkwilliams](https://archiveofourown.org/users/dkwilliams/gifts).



> Thanks to [GoldenUsagi](https://archiveofourown.org/users/GoldenUsagi/pseuds/GoldenUsagi) for the beta!

When Sherlock was five years old, he got his first chemistry set. It came in a leather carrying case with latches that opened with a satisfying _snick_ under his small fingers, and its glassware glittered at him with the lure of forbidden knowledge. He remembers, vividly, being instructed by a very solemn twelve-year-old Mycroft on how to use it. Mycroft had demonstrated the reaction of iron and copper (II) sulphate, and Sherlock had gasped as the copper precipitated seemingly from out of nowhere, branching out like bronchioles. It had been astonishing, something close to magic. 

He remembers, because it's the same way he feels when he looks at John.

//

He was doing chemistry when he met John, and the two have been paired in his mind ever since. He’d been testing for the presence of a particular blood antigen, indicative of a very rare genotype, when John limped through the door. For once, what was off the microscope slide was more intriguing than what was on it. He took John in at a glance, and in retrospect, was taken in turn.

He’s aware of the colloquial meaning of ‘chemistry’, of course, but he didn’t consider it relevant until much later.

//

They're in equilibrium with each other, a perfectly balanced equation. Part of him is afraid to upset it, but another part wants to discover what product their reaction would produce. Probably an explosive one.

He thinks about it occasionally, between cases. When he's bored.

Oh, all right, he thinks about it all the time.

//

He watches John even more carefully than usual, although he tries not to be obvious about it. He could swear he’s being watched in turn, though if he is, he’s never quite been able to catch John at it. But sometimes he glances up, and sees John’s pupils darken slightly, and wonders.

//

He said he plays the violin when he’s thinking, but now it would be more accurate to say he plays it when he’s thinking about John. He stays awake nights and pours his frenetic energy into the strings, summons hope and affection and yearning out of his violin’s dark places, like life out of the primordial deep. It’s evidence of the emotions few people believe him to possess, and he always keeps playing until John wakes up and walks in to bear witness. The pieces don’t feel finished without John there to hear them.

His entire life was an unresolved melody until John appeared.

//

John makes tea every morning, dependable as the foundations of London. Most mornings, Sherlock lies folded up in his chair and observes whilst John snipes companionably at him. John’s movements have a certain economy of motion that Sherlock finds aesthetically pleasing. He knows John would never call himself graceful, but then, John’s never seen himself make tea with practiced competence, or go running through back alleys after a sex offender, or fire a perfect shot with a handgun at twenty metres. 

John brings him his tea, fixed the way he likes it, and quirks an eyebrow at Sherlock in his peculiar mixture of mild disapproval and wry affection. Sherlock grunts an acknowledgement at John as he goes back into the kitchen for his own mug.

He watches John move about the flat and thinks about volumetric displacement, and wonders how it's possible for John's displacement to be so disproportionate to his size. 

//

After the third time his breathing shifts while watching John's shoulders move under his T-shirt as he makes tea, the threadbare fabric clinging lovingly to his trapezius muscles, Sherlock is willing to admit he has a problem.

John’s shoulders are so straight. Other people slouch or slump or hunch over, but John holds himself at perfect right angles. It’s how he must have looked to his men in Afghanistan, to the injured and dying people he saved: stance squared, braced against the desert like a stalwart wall.

He would have liked to have seen John there, in his element, several years and one bullet away from rearranging Sherlock’s life for him, but he has John here and now and that’s quite enough to be going on with.

He does wonder, though, if John still has the uniform.

//

He looks at John's clever, dexterous hands and thinks of embryology, of the delicate balance of hormones and growth factors in amniotic fluid that influenced the anatomy and physiology of this person in front of him, and knows that even Lamarck and Darwin would be at a loss to explain the marvel that is John.

John's hands are a paradox. They're so gentle and seeking when Sherlock is hurt, but so clenched and furious when he does the hurting. They're the hands that shot a man for him, the fingertips that bruised his wrist searching for a pulse, the knuckles that bloodied his unapologetic mouth.

He'd like to have John's hands at his mouth again, but not for punching.

//

John curls up in his chair like a cat when he reads. The firelight washes him in soft reds and golds and soaks into his jumper and hair. He looks so warm—he _is_ so warm, and Sherlock wants to curl up with him, bury his face in John’s jumper and nudge his head up into John’s hands so his nimble fingers can card through Sherlock’s hair.

He wants to read every word of the book that is John, from beginning to end. He wants to stroke his spine and the gilded edges of his pages.

//

John’s voice would seem unremarkable to most people, but Sherlock could pick it out of a crowd of hundreds. He feels it in his marrow when John speaks, down in the secret places where new erythrocytes are made. Every one resonates at the frequency of John’s voice, rushes out into Sherlock’s bloodstream and gathers in his fingertips in a desperate bid to get to John. All of Sherlock’s cells are imprinted with John’s words, pulsating in time with the molecules set vibrating by John’s vocal cords. He’s memorised the timbre of John’s voice when it drops low and dangerous with command, like a hawk stooping to its prey. Sherlock’s entire body knows the shape John’s mouth makes around his name.

John’s voice could fell armies, and probably has.

//

They’re at a crime scene, with cautionary police tape strung across the entrance like a promise made to be broken, but Sherlock can’t stop watching John. Objectively, John is quite ordinary-looking, but subjectively, to Sherlock, he’s beautiful—beautiful as the Fibonacci sequence, as Euler’s identity, as the sonorous curves of his violin.

After Sherlock gathers what evidence he needs, he goes to collect John. He’s crouched in the back garden, examining the blood left behind by the victim, but he turns when Sherlock walks outside. He offers a hand to pull John up to him, and Sherlock thinks about chirality as their palms clasp together, the handedness of molecules meant to interlock.

“Solved it yet?” John’s smiling at him, as if he knows that this is a foregone conclusion. It is, of course, but it’s unfailingly pleasant to have John think so.

“Yes. It was the ex-boyfriend. Lestrade’s on his way to arrest him. Find anything interesting?”

John huffs a self-deprecating laugh. “Other than the victim’s love of ugly shrubbery, no. Ready to go?”

He looks up at Sherlock, his whole face open in the way it only ever is around him, and Sherlock feels something stutter in his chest, his treacherous heart beating _johnJohn johnJohn johnJohn_. The sun’s setting behind John, but its dying light drowns itself in John’s eyes and wraps around his shoulders and narrow waist. The sight sparks an ignition behind Sherlock's eyes, at the top of his spine, and his dopaminergic pathways light up like Piccadilly Circus.

Sherlock clears his throat. “Yes,” he croaks, “let’s go home.”

//

He watches the buildings blur by behind John in the cab window, watery and indistinct, and remembers the first time he saw London. He was three years old, and the instant affinity he felt for this man-made amalgam of skin and steel filled him up and fascinated him like the tempestuous strains of Beethoven. London had its own music, its chaotic complexity humming around him like a beehive, and it was astounding that something so monolithic could also be so intricate and multi-faceted. He learned the City with the obsessive alacrity he reserves for truly precious things. Its buildings and roads became the foundational architecture of his mind palace, stratified levels of storage that would never be exhausted, because even the ancient Romans were just upstart colonists when they took Londinium. It’s deceptively simple from the outside, but even someone as brilliant as Sherlock could study it for a lifetime and never be bored.

John is the only person he’s ever met who reminds him of London.

//

He wants to analyse John's proteome, every single building block of his cells and his constituent chemicals, until he understands exactly which substances in John catalyse such a reaction in him, which ones induce affection and addiction and why they've never had an effect on him until they belonged to John Watson.

What aromatic compounds make up the way John smells? What is the pH of his saliva? What is the frequency and amplitude of his laugh? What is the equation for the steady arc of his shoulders? Which electrolytes are present in his sweat, and would it be more conductive when combined with Sherlock's? What is the specific gravity of his blood? When John looks at him, do John’s oxytocin levels rise? Do the adrenalin levels in his blood surge when Sherlock stands too close?

When Sherlock cares about something, he analyses it, takes it apart piece by piece. He dreams about doing the same to John.

//

When he stands close enough to John to share body heat, he wonders how quickly heat transfer would occur from John's skin to his own, whether it could be slowed down and prolonged for hours until they reached thermal equilibrium, entropically equal and inseparable in the eyes of science.

When he watches his chemical solutions change colour, he wonders what colour John's eyes would turn if Sherlock touched him.

When he picks up a few bruises on a case, he wonders what it would be like if John had been the one to mark him. Sherlock would be able to watch the evidence of John's desire for him being reabsorbed into his body as the bruising changed colour and slowly faded. Bruises bloom like ink in water on his pale skin. They’d be visible for over a week.

He wonders how it would feel to be held by John, or to curve around him in bed, whether all of Sherlock’s molecules would orient themselves toward John, mirroring their embrace on the microscopic level, looking for their counterparts, bonded forever.

He wonders what would happen if he pushed John flat onto the kitchen table. If he stocked it with all of his non-toxic but staining compounds first, and made sure to tip over every one with the force of their bodies, the multi-coloured marks would last for days, drenching their skin and streaking them with the evidence of what they’d done. Their hands, slender and sturdy respectively, would be soaked in variegated hues that everyone would see, flowing up from their fingertips which had absorbed the liquids from each other’s skin like wicks, like plant stems from the earth. They’d be caught, perhaps literally, red-handed. 

He wonders a lot of things. He can’t stop wondering.

//

It’s alchemical, the way he feels about John: initial regard transformed into something much more. Avicenna and the others thought they were changing dross into gold, but Sherlock doesn’t need misguided metaphysics to tell him that John is something precious, or that he’d purify a thousand compounds just to replicate the pyrite shine of his hair.

//

It's late afternoon, and it's sweltering. It’s mid-September but London is in the midst of a heat wave, so it's more than hot enough inside to make Sherlock irritable as he tries to identify the toxin found on the skin of Lestrade's latest murder victim. Sherlock is sweating, and if it gets any hotter in the flat, the reaction kinetics will be thrown off and he won't be able to do this until tomorrow. He can feel the curls at the nape of his neck growing damp, and a single drop of sweat runs down below his collar. The windows are already open, to no avail, and Mrs Hudson is out, so shouting for her to do something about the heat didn't help either. Even in pyjamas, this is intolerable, and he can barely concentrate. He's almost finished when the heat ratchets up just one more degree and his solution starts to precipitate out. Finally foiled, he lets out a bellow of frustration and slams his fist onto the table just as John walks through the door, home from the clinic. Sherlock freezes, caught, and immediately schools his face into a suitably contrite expression. John eyes him, considering, and walks through the sitting room and the kitchen to him.

"God, it's hot in here. What're you working on?"

Sherlock, still sitting, looks up at John. He likes John like this, artificially tall from Sherlock’s perspective, towering over him even though he's short. It's a pleasing symmetry to the unsettling, sentimental truth that John towers over him in other, more important ways as well, blocking out almost everything else.

Sherlock's staring, though, and he looks down just in time to see the last of his reaction product sink to the bottom of the beaker.

"Isolating the toxin from Lestrade’s latest case, but the heat ruined it. It's an irreversible reaction; I can't salvage it now."

"Sorry," John murmurs, and squeezes the nape of Sherlock's neck. Sherlock's breath hitches as his perception narrows entirely to the points of contact between John's fingertips and his fevered skin. He looks up at John, which is dangerous, but he can't help it. John seems caught, and his pupils are dilated. He looks flushed, and though he's beginning to sweat too, Sherlock doesn't think it's just from the heat. His own pupils dilate even further as he takes all this in, wonders about electrolytes again, combines it with John's hand on the back of his neck and John's shallow breathing to come to an astounding conclusion.

"John," he breathes, eyes still locked with John's. "You—"

"Yeah?" John asks, shakily, and the pad of his thumb sneaks up into Sherlock's hair.

"You want—are you really—"

"Yeah, I do," John replies when Sherlock can't produce anything else. "I am."

"Okay," Sherlock breathes, astonished, and then he's on his feet and they're kissing. John’s mouth is a revelation, and Sherlock wants to write the equations of motion for the way it moves against his, warm and thorough and perfect. John lavishes each of his lips with attention in turn, as if he’s had ages to make plans for what he would do to Sherlock’s mouth and is finally fulfilling them. Sherlock cups John’s jaw in his hands, keeping him where he wants him, and his fingertips explore the soft hidden skin behind John’s ears. John shivers and clutches at Sherlock’s hair, and Sherlock breaks the kiss to gasp and tilt his head back into the sensation. He can hear John make a feral sound at this, and his hands knead through Sherlock’s curls while his mouth goes straight to Sherlock’s exposed throat, mapping out every centimetre of it. When John bites gently at his Adam’s apple, Sherlock moans John’s name, his voice in its lowest register. John shudders against him, breaths flaring out quick and shallow against the hollow of Sherlock’s throat.

“Jesus,” John groans, “your voice is practically subsonic like this, _come here_ ,” and Sherlock has never been happier to comply with an order in his life.

John lifts the hem of Sherlock’s sweat-damp T-shirt and peels it over his head, and Sherlock still feels hot but it's an entirely different heat now, trickling down his spine and settling molten in the cradle of his hips. John looks overcome at the sight of him, barely halfway undressed, and Sherlock thinks he may spontaneously combust if he doesn't start touching John again immediately. Sherlock reaches out, and then John’s hands are on him, roving over his torso, a declaration of intent that makes his belly tighten with need. His hands find John’s hair and he slots their mouths together, licking his way assiduously into John's mouth, desperate to find out how he tastes and whether Sherlock can estimate the pH of John’s saliva using just his tongue. He can't, he'll need samples, but this is already the best experiment he's ever undertaken.

John moans into his mouth and spins him around until he's facing the cupboards. He licks up the back of Sherlock's neck to the point of his hair, and when he starts kissing and biting softly Sherlock is very glad he's near a supporting surface, because his knees nearly give out. John winds an arm around his waist to steady him, and his mouth moves down between Sherlock’s shoulder blades. Sherlock shivers, and he's sure he can feel the electrical potential gathering where their bodies touch, conduction crackling at the surface of his skin. His limbic system is drowning in reward chemicals, and warmth is blossoming outward from his sternum like blood in water, insidious and lovely, until he can no longer tell where he ends and John begins, because diffusion has done its work and he's woven together with John at a molecular level.

Sherlock turns in John’s arms to recapture his mouth and flips them so John’s back is against the countertop. He proceeds to break John down into his constituent parts just as thoroughly as he dreamed of doing, and John gives as good as he gets, sucking a mark onto Sherlock’s neck and stroking the small of his back, fingertips slipping below his waistband. Sherlock makes a deeply appreciative sound at this and presses in even closer, but still not close enough. He unbuttons John’s shirt and tugs it off, fumbling but reverent, and is rewarded by the sight of John’s chest suffused with a deep blush, all the blood in his skin rushing upwards to meet Sherlock’s questing mouth. Sherlock kisses everywhere he can reach, skims the freckled tops of John’s shoulders with his mouth and learns the shape of his scar against his tongue. He pulls back to press his fingertips gently, wonderingly against John’s flushed throat just to see the paleness appear and then disappear when the blood flows back in, rosy under his skin. John takes Sherlock’s hand and kisses the pads of his fingers, the centre of his palm, the circumference of his wrist. Sherlock watches, dumbstruck, as John’s lashes drop over his eyes in evident bliss, and he has to remind himself to breathe.

There’s no sound in the room except their ragged breathing, and John is tracing the bow of Sherlock’s lips now, venerating his mouth. He draws Sherlock back in, thumbs stroking his cheekbones, and tenderly kisses the corner of his mouth. Sherlock whimpers, undignified, and kisses back, tugging John’s lower lip delicately between his teeth and then soothing it with his tongue, coaxing John’s mouth open. John tilts his hips up in supplication, and Sherlock takes the invitation, strips off John’s trousers and pants and puts his violinist’s hands to a new use. The crests of John’s hipbones notch into Sherlock’s palms like they were made to fit there, and John’s skin is even warmer here, exothermic for Sherlock. He learns what will make John gasp and arch up into his hands, what will make his mouth fall open and his head tip back. John’s irises are all but eclipsed by his blown pupils, and he’s making sounds that Sherlock will hear in the back of his mind for weeks. He can feel every tiny movement of John’s body vibrating up through his fingertips, resonant and sweet, and John quivers under his touch like his violin. He can feel John’s whole body drawing up tight like a bow, and a vertiginous thrill starts at the base of Sherlock’s spine in response.

When John cries out his name, Sherlock feels the way elemental sodium must when it hits water.

//

Later, when they’ve ended up on the floor, Sherlock looks up past where John is sprawled on top of him, half-asleep, to the spent beaker that catalysed this consummation, and starts to laugh. He feels amazing, like he’s just solved the world’s most complicated case, or played all of Paganini’s Caprices without a single mistake. He feels bigger than himself, as if he's expanding faster than the boundaries of his body. He could encompass the universe like this, see every star and molecule, and still find nothing more fascinating than John. He knows he’ll wake John if he doesn’t stop laughing, but he can’t control it. He thinks it might be simple happiness.

John stirs and pushes himself up on his hands over Sherlock. He can see the thoughts flickering behind John’s eyes like a burgeoning candle flame, going from confusion to satisfaction to what looks like joy.

“What’s so funny?” John says, gently, and brushes a hand down Sherlock’s throat, tracing his suprasternal notch with his thumb. This is novel and marvellous, and Sherlock finally stops laughing so that he can record the sensation in his mind palace, in the newly expanded room for John-Induced Somatosensory Feedback. When he’s done, he waves a hand in the direction of the table.

"Do you see, John? Do you get it? We're like those reactants. We—"

"Can't be separated, yeah, I get it," John says, grinning wildly. "I think that's a solution I can work with."

Sherlock groans at the pun, and then groans for a completely different reason when John ducks his head and does something very cunning to the edge of Sherlock’s collarbone.

“Your hypothesis has merit,” gasps Sherlock, “but it could do with further study.”

If possible, John’s grin grows even wider. He looks incandescent, like Sherlock feels, as if his heart has just reached critical mass.

“A long-term study, then? For science?”

Sherlock nods vehemently and curls his palms over the tops of John’s shoulders, thumbs anchored on his collarbones, pulling him back down. “Yes, yeah, let’s do that,” Sherlock babbles, shoving the words out between heaving breaths. 

“Scientific progress waits for no man,” John laughs as he lowers his head, and Sherlock finds himself in euphoric agreement.


End file.
